What will the far future look like? For actor Will Smith and his son Jaden, the next generation could mark a "tipping point" for the environment. For futurist Ray Kurzweil, solar power is the solution to our energy ills. But for a look at the really far future, turn to Elon Musk, the billionaire founder of SpaceX and Tesla Motors. He's already thinking about spreading out from Earth to other planets — and engaging the warp drive to get to other star systems.

"There's some potential, even though it sounds science-fictiony, for warp drive to work," Musk said on Tuesday during a Google+ Hangout to publicize "After Earth," Smith's upcoming movie. "Technically, to warp space such that you're traveling at the speed of light, but you've warped space so that space is actually traveling."

Musk was referring to recent studies updating the "Star Trek" conception of warp travel, in which a whole region of the space-time continuum zips along at faster-than-light speeds. Researchers at NASA's Johnson Space Center say the idea isn't as crazy as it sounds, and they're trying to create space-time perturbations on a microscopic scale.

Even NASA Administrator Charles Bolden is on board: "One of these days, we want to get to warp speed," he said last September. "We want to go faster than the speed of light, and we don't want to stop at Mars."

Musk, however, sees Mars as a key stop on the path to turning humanity into a multiplanet species. "Either we're a spacefaring civilization, or we're going to be bound to Earth until some eventual extinction event," he said Tuesday.

All this meshes with the plot of "After Earth," in which Will and Jaden Smith play a father and son who find themselves back on Earth a millennium after cataclysmic events forced humanity to find refuge in a distant star system. The filmmakers organized the Hangout to give the Smiths as well as Musk, Kurzweil and environmentalist Alexandra Cousteau a chance to reflect on humanity's future. (It was also a chance to give the movie some publicity on the day "after Earth Day.")

After crash landing on a habitable planet abandoned by humans a thousand years before, a father and son explore their dangerous surroundings. "After Earth" opens May 31.

Will Smith on working with his son on the movie: "It was wonderful for the two of us to become environmentally educated together. ... The huge question of water came up: the idea that today it's oil that we're willing to go to war over, and at some point in the future, it's going to be water."

Jaden Smith, 14, on the challenges facing the next generation: "Our world is going to get to a tipping point ... if we want to stop that, then my generation would have to almost become obsessed with it, and say we're stopping everything that we're doing wrong right now: no more plastic, only reusable sources, only solar power."

Alexandra Cousteau, granddaughter of Jacques-Yves Cousteau: "We're on the knife's edge of either protecting this place where we live, or losing an enormous amount of it. But I have to say I completely agree with Jaden, in that this generation has an extraordinary opportunity to use technology that we've never had before ... to actually take control of our use of resources."